Rails 3 ActionMailer and Wicked_PDF

WickedPDF can render to a file just fine to attach to an email or save to the filesystem.

Your method above won't work for you because generate_pdf is a method on the mailer, that returns a mail object (not the PDF you wanted)

Also, there is a bug in ActionMailer that causes the message to be malformed if you try to call render in the method itself

http://chopmode.wordpress.com/2011/03/25/render_to_string-causes-subsequent-mail-rendering-to-fail/

https://rails.lighthouseapp.com/projects/8994/tickets/6623-render_to_string-in-mailer-causes-subsequent-render-to-fail

There are 2 ways you can make this work,

The first is to use the hack described in the first article above:

def email_invoice(invoice)
  @invoice = invoice
  attachments["invoice.pdf"] = WickedPdf.new.pdf_from_string(
    render_to_string(:pdf => "invoice",:template => 'documents/show.pdf.erb')
  )
  self.instance_variable_set(:@lookup_context, nil)
  mail :subject => "Your Invoice", :to => invoice.customer.email
end

Or, you can set the attachment in a block like so:

def email_invoice(invoice)
  @invoice = invoice
  mail(:subject => 'Your Invoice', :to => invoice.customer.email) do |format|
    format.text
    format.pdf do
      attachments['invoice.pdf'] = WickedPdf.new.pdf_from_string(
        render_to_string(:pdf => "invoice",:template => 'documents/show.pdf.erb')
      )
    end
  end
end

I used of Unixmonkey's solutions above, but then when I upgraded to rails 3.1.rc4 setting the @lookup_context instance variable no longer worked. Perhaps there's another way to achieve the same clearing of the lookup context, but for now, setting the attachment in the mail block works fine like so:

  def results_email(participant, program)
    mail(:to => participant.email,
         :subject => "my subject") do |format|
      format.text
      format.html
      format.pdf do
        attachments['trust_quotient_results.pdf'] = WickedPdf.new.pdf_from_string(
          render_to_string :pdf => "results",
               :template => '/test_sessions/results.pdf.erb',
               :layout => 'pdf.html')
      end
   end
  end